Victoria’s Dark Matter Lab Taking Shape

With the concrete slab now in place, the Stawell Underground Physics Laboratory (SUPL), is on schedule to complete construction by Christmas this year. This lab will be the Southern Hemisphere’s first underground dark matter laboratory, located one kilometre below ground at the now-retired Stawell gold mine in the Wimmera region of Victoria. 

Dark matter - or invisible matter as it is better described - is the majority of the material that makes up the Universe. Only a small portion of the Universe is made of what is considered “normal” matter - the matter made of atoms formed by protons, neutrons, and electrons, which is the stuff we see around us like stars, galaxies, humans, planets, moons, etc.

The rest of the universe consists of this yet-to-be-observed dark matter, which doesn’t give off or interact with any electromagnetic radiation. Scientists know that this elusive matter is out there because we can indirectly observe its gravitational effects on galaxies and their movements. Dark matter labs like SUPL aim to detect and figure out exactly what dark matter is. 

The five research institutions that will work at SUPL are Melbourne University, Swinburne University of Technology, Adelaide University, the Australian National University and the Australian Nuclear Science and Technology Organisation (ANSTO). 

“Science goes to extreme lengths to find answers, and in this case, to a very sheltered environment a kilometre underground,” said ANSTO’s representative on the SUPL company board, Professor Andrew Peele.

“It is impressive to see the progress made first-hand and pleasing to see the preparations for the range of activities that will advance our understanding of dark matter.”

Professor Peele accompanied Dr Leonie Walsh on a visit to the lab to see the construction first-hand. Dr Walsh is a  representative on the Forum of Australian Chief Scientists as interim chair of the company that will operate and manage the SUPL. 

It took them half an hour to journey down to the lab site, with strict safety inductions and personal protective equipment. Dr Walsh commented on how the lab’s scientists will have to go through similar experiences to reach the lab when it is complete. 

“Researchers will start their day with a 10-kilometre drive down a maze of tunnels in protective equipment to the cavernous laboratory, 1,100 meters underground to work on their dark matter experiments with equipment designed and built for the purpose of finding dark matter – this thing that makes up 85 percent of our universe, but which continues to be a mystery,” she said.

Dr Walsh also commented on the uniqueness of the underground lab site and its construction.   

“We saw the cavern walls where the lab is being built, being sprayed with a product called Tekflex to reduce the potential for interference from background radon gas in the rock mass, in experiments.” 

“As an industrial scientist, I have worked across a broad range of industrial sites around the world, but none as unique as SUPL.”

The lab, once completed, will be 33 metres long by 10 metres wide, and will house a SABRE detector. SABRE (Sodium-iodide with Active Background REjection) is an experiment that looks for the visible light that should be emitted as dark matter particles collide with a highly sensitive crystal target. 

The purpose of this experiment will be to attempt to replicate data produced in existing northern hemisphere dark matter observatories. SABRE was discussed at the new Australian Research Council’s (ARC) Centre of Excellence for Dark Matter Particle Physics first annual meeting late last year.

SUPL, where SABRE will be used, is funded by a \$10 million grant from the Federal and State Governments and supported by \$35 million funding from the Australian Research Council for the Centre of Excellence for Dark Matter Particle Physics based at the University of Melbourne. 

Tom Kelly, the University of Melbourne’s Senior Project Manager, said that the major parts of SUPL, as well as plumbing, electrical and communications cabling, and mechanical ductwork and piping, are expected to be in place by October.  

“We anticipate the handover to be on time and to commence the installation of experimental equipment before Christmas,” Mr Kelly said.